MAKING AND LAYING SUBMARINE CABLES . 167 
When the depths are uniform, soundings can be taken at 
points very far apart; but with variable depths they should 
be taken at least every two or three miles, until the greatest 
depth is reached, which generally remains the same for a con¬ 
siderable distance. 
Another matter to carefully consider is the choice of good 
landing places for the cables. These should be where the 
Fig. 107. 
anchors of vessels are not liable to break the cable, and where 
there are no rocks on which the cable may be worn through by 
the motion of the water that always takes place near the shore. 
The cable should also be connected at the nearest possible 
distance with the earth-line at a telegraphic office or station. 
The cable must be made with the requirements of the route 
it has to follow in view, and we have already shown why light 
cables do not serve for even moderate depths, where the bottom 
is always irregular. A heavy cable must be used whenever the 
depth is less than 800 yards. 
